1. Field of the Invention
The present invention is directed to a process for preparing a building and/or construction material; to a polymer modified aqueous dispersion; and to the use thereof for the preparation of a building and/or construction material.
The characteristics of a building and construction material, which hardens with water, depend in general on the characteristics of the binder matrix. This matrix is responsible that the aggregates as well as occasionally the reinforcing elements, fibers, wires, networks and so on, are bonded together as well as possible. The porosity of this matrix is responsible for the stability, the durability, the wear resistance and many other use characteristics. Thereby the porosity is in a reverse relation to quality and durability, i.e. the lower the porosity the higher the quality and the durability, respectively.
According to the Austrian Patent No.312 490 and the Swiss Patent No.574 880 such matrix, having the highest stabilities, may be achieved by adding amorphous silicon dioxide and a water reducing agent to the cement. In the DE-OS No. 33 43 948 it is suggested to add such a mixture in the form of a slurry to the concrete, in order to prepare together with an air entraining admixture an air entrained concrete without loss of strength. However, without a further stabilization these mixtures cannot be stored over a long period of time because they gelatinize and thereby they can only be processed further with the highest difficulties.